Fountain pen



FIG. 1 is a front elevational view of a fountain pen showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a side elevational view thereof from the left of FIG. 1;

FIG. 4 is a side elevational view thereof from the right of FIG. 1;

FIG. 5 is an enlarged top plan view thereof; and,

FIG. 6 is an enlarged bottom plan view thereof;

The broken lines showing the bottom of the fountain pen in FIG. 6 are included for the purpose of illustrating environment and form no part of the claimed design. 

The ornamental design for a fountain pen, as shown and described. 